Use wx's vendored copy of zlib rather than having a second copy in a submodule

.gitmodules

@@ -2,10 +2,6 @@
 	path = vendor/freetype2
 	url = git://git.sv.nongnu.org/freetype/freetype2.git
 	ignore = dirty
-[submodule "zlib"]
-	path = vendor/zlib
-	url = git://github.com/madler/zlib.git
-	ignore = dirty
 [submodule "wxWidgets"]
 	path = vendor/wxWidgets
 	url = git://github.com/wxWidgets/wxWidgets.git

build/DefaultConfiguration.props

@@ -61,6 +61,6 @@
     <IcuSrcDir>..\..\vendor\icu\source</IcuSrcDir>
     <LibassSrcDir>..\..\vendor\libass</LibassSrcDir>
     <WxSrcDir>..\..\vendor\wxWidgets</WxSrcDir>
-    <ZlibSrcDir>..\..\vendor\zlib</ZlibSrcDir>
+    <ZlibSrcDir>..\..\vendor\wxWidgets\src\zlib</ZlibSrcDir>
   </PropertyGroup>
 </Project>

build/zlib/zlib.vcxproj

@@ -24,9 +24,33 @@
     <InstallHeaderTo Include="$(MSBuildThisFileDirectory)\zconf.h" />
   </ItemGroup>
   <ItemGroup>
-    <ClCompile Include="$(ZlibSrcDir)\*.c" />
+    <ClCompile Include="$(ZlibSrcDir)\adler32.c" />
+    <ClCompile Include="$(ZlibSrcDir)\compress.c" />
+    <ClCompile Include="$(ZlibSrcDir)\crc32.c" />
+    <ClCompile Include="$(ZlibSrcDir)\deflate.c" />
+    <ClCompile Include="$(ZlibSrcDir)\gzclose.c" />
+    <ClCompile Include="$(ZlibSrcDir)\gzlib.c" />
+    <ClCompile Include="$(ZlibSrcDir)\gzread.c" />
+    <ClCompile Include="$(ZlibSrcDir)\gzwrite.c" />
+    <ClCompile Include="$(ZlibSrcDir)\infback.c" />
+    <ClCompile Include="$(ZlibSrcDir)\inffast.c" />
+    <ClCompile Include="$(ZlibSrcDir)\inflate.c" />
+    <ClCompile Include="$(ZlibSrcDir)\inftrees.c" />
+    <ClCompile Include="$(ZlibSrcDir)\trees.c" />
+    <ClCompile Include="$(ZlibSrcDir)\uncompr.c" />
+    <ClCompile Include="$(ZlibSrcDir)\zutil.c" />
   </ItemGroup>
   <ItemGroup>
-    <ClInclude Include="$(ZlibSrcDir)\*.h" />
+    <ClInclude Include="$(ZlibSrcDir)\crc32.h" />
+    <ClInclude Include="$(ZlibSrcDir)\deflate.h" />
+    <ClInclude Include="$(ZlibSrcDir)\gzguts.h" />
+    <ClInclude Include="$(ZlibSrcDir)\inffast.h" />
+    <ClInclude Include="$(ZlibSrcDir)\inffixed.h" />
+    <ClInclude Include="$(ZlibSrcDir)\inflate.h" />
+    <ClInclude Include="$(ZlibSrcDir)\inftrees.h" />
+    <ClInclude Include="$(ZlibSrcDir)\trees.h" />
+    <ClInclude Include="$(ZlibSrcDir)\zconf.h" />
+    <ClInclude Include="$(ZlibSrcDir)\zlib.h" />
+    <ClInclude Include="$(ZlibSrcDir)\zutil.h" />
   </ItemGroup>
 </Project>

vendor/zlib

@@ -1 +0,0 @@
-Subproject commit 50893291621658f355bc5b4d450a8d06a563053d